Opioids Agonists (Exam II) Flashcards
(40 cards)
What are opioids effects on the CO₂ medullary center?
- Opioids inhibit the CO₂ medullary center.
Differentiate opioids from narcotics.
- Opioids = all exogenous substances that bind to endogenous opioid receptors.
- Narcotic = any substance that can produce dependence (stupor)
What two types of opioid chemical structures are there?
- Phenanthrenes
- Benzylisoquinolines
What types of drugs are Phenanthrenes?
What types of drugs are benzylisoquinolines?
- Phenanthrenes: Morphine & codeine
- Benzylisoquinoline: Papaverine
What is papaverine mostly used for?
Treating intra-arterial barbiturate administration (dilates the highly constricted artery).
What portions of the brain are the source of descending inhibitory signals?
- Thalamus
- PAG
- Locus Coeruleus
What endogenous substances have the same effect as opioids?
Endorphins, Enkephalins, and Dynorphines.
Presynaptic inhibition of what neurotransmitters occurs with opioid administration?
- ACh
- Dopamine
- NE
- Substance P
How do opioids modulate pain at the cellular level?
At pre/postsynaptic opioid receptor sites in CNS
- ↑ K⁺ permeability (hyperpolarization)
- inactivate Ca⁺⁺ channel
Where are opioid receptors located in the brain?
- PAG
- Locus Coeruleus
- RVM (rostral ventral medulla)
- Hypothalamus
Where is the primary site of opioid receptors in the spinal cord?
Substantia gelatinosa (aka Laminae 2)
Where is/are opioid receptors found outside the CNS?
- Sensory neurons & immune cells
What are the four (most important) types of opioid receptors?
- Μu1 (μ₁)
- Μu2 (μ₂)
- Κappa (κ)
- Delta (δ)
Which opioid receptor(s) is/are responsible for respiratory depression & physical dependence?
- Μu2 and δ
Which receptors are responsible for constipation?
- Μu2 primarily
- δ (less)
Which receptors can cause urinary retention?
Are there any receptors that cause diuresis when bound?
- Retention: Μu1 and δ
- Diuresis: κ
All opioid receptors induce analgesia at both the brain and the spinal cord. T/F?
- False. Μu2 receptors only cause analgesia at the spinal cord level.
What opioid receptors have low abuse potential when bound?
Μu1 and κ
Which opioid receptor is responsible for euphoria, bradycardia, hypothermia, and miosis when bound?
Mu1
What agonists bind to each of the four opioid receptors?
- Mu1 & Mu2 = endorphins, morphine, synthetics.
- κ = dynorphins.
- δ = enkephalins.
Describe the adverse side effects of opioids on the cardiovascular system.
- ↓BP from ↓SNS tone
- ↓HR or histamine release = ↓BP
What possible cardiovascular benefits do opioids provide?
- Myocardial ischemia protection (decrease oxygen demand)
What are the respiratory effects of opioids?
What would symptoms of overdose be?
- Depressed CNS response to CO₂ causing a right shift of PaCO₂ (↑)
- Overdose = apnea, miosis, coma.
What drug would treat opioid ventilatory depression but not reverse analgesia?
How?
- Physostigmine would by increasing CNS ACh levels.
